1. Field of the Invention
The present invention relates to the provision of novel and unique Land Grid Array (LGA) interposers, which incorporate the structure of metal-on-elastomer hemi-torus and other geometrically configured electric contacts to facilitate an array of interconnections between diverse electrical components. The invention is further concerned with a method of producing the inventive LGA interposers.
Land Grid Array (LGA) interposers, by way of example, provide an array of interconnections between a printed wiring board (PWB) and a chip module, such as a Multi-Chip Module (MCM), among other kinds of electrical or electronic devices. LGA interposers allow connections to be made in a way which is reversible and do not require soldering as, for instance, in ball grid arrays and column grid arrays. Ball grid arrays are deemed to be somewhat unreliable on larger areas because the lateral thermal coefficients of expansion driven stresses that develop exceed the ball grid array strength. Column grid arrays hold together despite the stresses but are soldered solutions and, thus, do not allow for field replaceability, which is important because it saves the customer or user significant costs in the maintenance and upgrading of high-end computers for which LGAs are typically used.
2. Discussion of the Prior Art
The basic concept of utilizing LGA interposers to provide an array of electrical connections is well known in the technology. In this connection, reference may be made in particular to Hougham, et al., U.S. Patent Publication No. 2005/0106902 A1, which is commonly assigned to the assignee of this application, and the disclosure of which is incorporated herein by reference in its entirety. This publication describes LGA interposers which define structure consisting of metal-on-elastomer type electrical contacts, wherein a compliant contact consists of an elastomeric material structural element partially coated with an electrically conductive material, preferably such as a metal, so as to form the intended electrical contact. However, there is no disclosure nor suggestion of a compliant contact of an LGA interposer type providing multiple points of electrical contact for each gridpoint in a configuration, such as is uniquely provided by the present invention.
Johnescu, et al., U.S. Patent Publication No. 2005/0124189 A1 discloses an LGA-BGA (Land Grid Array—Ball Grid Array) connector housing and electrical contacts which, however, do not in any manner disclose the novel and inventive LGA interposer metal-on-elastomer structure as provided for herein.
Similarly, DelPrete, et al., U.S. Pat. Nos. 6,790,057 B2 and 6,796,810 B2; and Goodwin, et al., U.S. Pat. No. 6,293,810 B2, describe various types of elastomeric electrical contact systems and devices which, however, do not at all disclose the features and concept of the present inventive metal-on-elastomer LGA interposers and arrays pursuant to the present invention.